This Small Business Innovation Research project addresses the development of a novel, low-cost monitor for organophosphate-based pesticide exposure. Organophosphate pesticides are highly toxic compounds used to control insect populations in a number of agricultural and landscaping applications. Workers are exposed to these chemicals during pesticide manufacture, transport, mixing, and application. Exposure can occur via three pathways: oral, dermal, and inhalation. The proposed monitor will measure vapor phase concentration. Selective chemiresistor microsensors for detecting organophosphate based pesticides (e.g., Terbufos and Diazinon) will be developed during Phase I. The response characteristics of prototype devices will be evaluated and optimized in the presence of these chemicals as well as water vapor and other gas- phase interferents commonly found in real-world environments. Detection limits, response time, sensor stability, and other key performance metrics will be determined. Phase I results will prove the feasibility of developing a stand-alone personal exposure monitor during Phase II. The personal monitor developed under this program will provide real-time detection of organophosphate pesticides. Cost-effective and accurate monitoring will allow workers to identify and avoid dangerous situations. Integrated data-logging capabilities will provide employers, regulators, and researchers with reliable exposure records. [unreadable] [unreadable] [unreadable] [unreadable]